Y-frame external bone fixator

ABSTRACT

In an embodiment of the invention, a fixator for fixating bone fractures includes a Y-frame having superior, anterior and posterior arms. The arms may be slotted and may accept mounting hardware for supporting fixation pins or transfixion pins. Various components of mounting hardware may be able to be adjusted either in discrete steps or in continuous manner, for various degrees of either translation or rotation. The Y-frame may be rigid, or may have joints that allow either angulation or arm-twisting adjustment. Arms may be provided joinable interchangeably to a hub. A kit of such parts may be provided.

FIELD OF THE INVENTION

The invention pertains to bone fixation. More specifically, theinvention relates to external frames and hardware used for thestabilization of bones in a variety of medical situations.

BACKGROUND OF THE INVENTION

The terminology and descriptions contained herein are principally withinthe art field of, and for those skilled in the art of, orthopedicmedicine. As such, only brief explanations of known subject matterwithin this art field will be provided because the details will be wellknown to those skilled in this art. The present invention, however, willbe thoroughly described.

External bone fixation incorporates the use of certain structures andinstruments to assist in bone surgery as an alternative or an adjunct tointernal fixation. External fixation is also used in situations thatprohibit the use of internal fixation such as infection and open wounds,as well as in cases of severe deformity where acute deformity correctionis not possible. In the lower extremity, for example, an externalfixation construct can be used for fusion surgery as well as anystabilization or distraction procedure, and fracture repair.

One well known external fixator is called the Ilizarov frame, comprisedof one or more round rings. This, and other types of similar externalsystems, have been in use for many years. They rely on wires and pinsplaced into the bones of a patient, that are then attached to the ringsor other structures outside of the patient's body. The rings or otherstructures are then interconnected to form an overall external fixationconstruct.

In the foot, for example, smaller external fixators are more desirablebecause they are better able to fixate the smaller bones of the footthan a large and bulky Ilizarov-type ring fixator. And overall, attemptsover the years to create a simple to use, and simple to teach to medicalprofessionals, external fixation system that can be used for extremitysurgery in general, and foot surgery in particular, are not believed tohave yielded optimal results. Thus, it continues to be desirable toimprove certain design features of external fixation for improvedsurgeon usability and improved patient outcomes.

SUMMARY OF THE INVENTION

In an embodiment of the invention, an apparatus for fixating a boneincludes a Y-frame having a superior arm, an anterior arm and aposterior arm rigidly joined to each other at a central junction. Thesuperior arm has a superior arm axis generally along a lengthwisedirection of the superior arm, and a superior arm slot therethrough thatextends generally along a portion of a length of the superior arm,defining a superior arm slot plane. The anterior arm has an anterior armaxis generally along a lengthwise direction of the anterior arm, and ananterior arm slot therethrough that extends generally along a portion ofa length of the anterior arm, defining an anterior arm slot plane. Theposterior arm has a posterior arm axis generally along a lengthwisedirection of the posterior arm, and a posterior arm slot therethroughthat extends generally along a portion of a length of the posterior arm,defining a posterior arm slot plane. The superior arm axis, anterior armaxis and posterior arm axis intersect at a common intersection point andoccupy a common plane. None of the superior arm axis, the anterior armaxis and the posterior arm axis are collinear with each other. Theapparatus also includes mounting hardware mountable on the arms throughtheir respective slots. The mounting hardware is able to occupy aplurality of translational positions along the slots, and is suitablefor holding pins that fixate the bone.

In various embodiments, the apparatus further comprises a superior armside hole or a superior arm end hole or an anterior arm side hole or ananterior arm end hole or a posterior arm side hole or a posterior armend hole.

In an embodiment, the apparatus further comprises a central axis holeperpendicular to the common plane, and passes through the commonintersection point of the arms.

In an embodiment, the Y-frame comprises a radiolucent material andcomprises, in the radiolucent material, markers in desired locations,the markers being made of a radiopaque material.

In an embodiment, the mounting hardware comprises a clamp having a clampcross-hole having internal grooves having a clamp hole angular spacingof the internal grooves, and comprises a rocker nut having an externaltooth engageable with the clamp cross-hole having internal grooves.

In an embodiment, the mounting hardware comprises a pin-holding assemblythat provides adjustability in at least five total degrees of freedom oftranslation and rotation, and comprises a clamping bolt that providesadjustability in fewer than five total degrees of freedom of translationand rotation.

In various embodiments at least one of the arms comprises repeatedfeatures, the mounting hardware comprises shim washers, and at least oneof the shim washers has a complementary underside feature that iscomplementary with the repeated feature. In an embodiment, the repeatedfeatures in the arm are grooves are generally parallel to each other,and the complementary underside feature comprises complementary grooves.In an embodiment, the repeated features are countersinks in the arm andthe complementary underside feature comprises a protrusion that isconical or partially conical. In at least some rotational orientationsof the shim washer relative to the arm, the complementary feature canengage with the repeated features, and, in at least some otherrotational orientations of the shim washer relative to the arm, thecomplementary feature can avoid engaging with the repeated feature. Inan embodiment, the mounting hardware comprises a yoke that includes acomplementary underside feature on an underside of the yoke that iscomplementary with the repeated feature. In an embodiment, the mountinghardware comprises a pin-holding apparatus comprising a yoke having aninternal taper and comprises a clamp having an external tapercomplementary to the internal taper, where the clamp is disposed to gripa pin upon action of the internal taper against said external taper. Inan embodiment, the external taper on the clamp is a segment of a conicalsurface, and the internal taper inside the yoke is a segment of aconical surface.

In an embodiment of the invention, the mounting hardware comprises shimwashers, and the shim washers have nesting features suitable to nestwith other shim washers when stacked. In an embodiment, the mountinghardware further comprises a yoke, and the yoke has a nesting featuresuitable to nest with one of the shim washers.

In another embodiment of the invention, an apparatus for fixating a boneincludes a Y-frame comprising a superior arm, an anterior arm and aposterior arm, the arms having respective arm axes generally alongrespective lengthwise directions of the arms, The superior arm, anteriorarm and posterior arm are individual components that are separatelyattachable to a hub. The apparatus also includes mounting hardware thatis mountable on the arms and suitable for holding pins that fixate thebone. In an embodiment, the hub comprises, on its external surface,planar surfaces and at least some of the arms comprise, on a respectivehub-facing surface, shapes that are complementary to the hub and arecapable of interacting with the hub grooves to constrain a configurationof the arms relative to the hub. In an embodiment, the hub comprises, onits external surface, a surface that is not smooth, and at least one ofthe arms comprises, on its hub-facing surface, a surface that iscomplementary to the hub surface, and at least another one of the armscomprises, on its hub-facing surface, a smooth surface that does notengage with the hub-facing surface. In an embodiment, the hub comprises,on its external surface, hub grooves, and at least some of the armscomprise, on a respective hub-facing surface, hub-facing grooves thatare complementary to the hub grooves and are capable of interacting withthe hub grooves to constrain a configuration of the arms relative to thehub. In an embodiment, the hub grooves comprise a first set of groovesparallel to each other. In an embodiment, the hub grooves furthercomprise a second set of grooves parallel to each other and generallyperpendicular to grooves in the first set of grooves. In an embodiment,the apparatus further comprises attachment means for attaching the armsto the hub.

In another embodiment of the invention, an apparatus for fixating a boneincludes a first Y-frame that comprises a superior arm, an anterior armand a posterior arm, the arms having respective arm axes generally alongrespective lengthwise direction of the arms. None of these axes arecollinear with each other, and the axes intersect at a commonintersection point and occupy a common first Y-frame plane. Theapparatus further includes a second Y-frame, that comprises a superiorarm, an anterior arm and a posterior arm, the arms having respective armaxes generally along respective lengthwise direction of the arms. Noneof these axes are collinear with each other, and the axes intersect at acommon intersection point and occupy a common second Y-frame plane. Inaddition, the apparatus includes a transfixion pin anchored at or near afirst end to the first Y-frame and anchored at or near a second end tothe second Y-frame. The first Y-frame plane and the second Y-frame planeare constrained through the transfixion pin to be parallel to eachother. In an embodiment, the first Y-frame has a flat surface on one ofits arms, the second Y-frame has a flat surface on one of its arms, andthe transfixion pin is anchored in direct contact with each of theseflat surfaces. In an embodiment, each arm has a slot and a clamping boltdisposable within the slot that maintains the first Y-frame and secondY-frame parallel to each other by the constraint through the transfixionpin. In an embodiment, each arm has a slot and a clamping boltdisposable within the slot such that the clamping bolt is prevented fromrotating about its own lengthwise axis within the slot. In anembodiment, the first Y-frame and second Y-frame are identical to eachother. In an embodiment, the apparatus further comprises a pin-holdingapparatus suitable for holding a fixation pin for fixating the bone.

In another embodiment of the invention, an apparatus for fixating a boneincludes a first Y-frame that comprises a superior arm, an anterior armand a posterior arm, the arms having respective arm axes generally alongrespective lengthwise direction of the arms, None of these axes arecollinear with each other, and the axes intersect at a commonintersection point and occupy a common first Y-frame plane. Theapparatus further includes a second Y-frame comprising a superior arm,an anterior arm and a posterior arm, the arms having respective arm axesgenerally along respective lengthwise direction of the arms. None ofthese axes are collinear with each other, and the axes intersect at acommon intersection point and occupy a common second Y-frame plane. Inaddition, the apparatus includes a transfixion pin anchored at or near afirst end to the first Y-frame and anchored at or near a second end tothe second Y-frame. The first Y-frame plane and the second Y-frame planeare constrained through the transfixion pin to a defined relativeorientation to each other with respect to a rotational axis that is alongitudinal direction of the transfixion pin. In an embodiment, theapparatus comprises a transfixion pin extending between the firstY-frame and second Y-frame, and the transfixion pin is grasped at ornear each of its ends by a respective clamping bolt. In an embodiment,the transfixion pin has a first flat region in a first clamped portionof the transfixion pin and a second flat region in a second clampedportion of the transfixion pin, the first flat region and second flatregion being parallel to each other. In an embodiment, the transfixionpin has a first flat region in a first clamped portion of thetransfixion pin and a second flat region in a second clamped portion ofthe transfixion pin, the first flat region and second flat region beingcoplanar with each other. In an embodiment, the transfixion pin has afirst flat region in a first clamped portion of the transfixion pin anda second flat region in a second clamped portion of the transfixion pin,the first flat region and second flat region lying in a plane that isparallel to a long axis of the pin. In an embodiment, the transfixionpin has a first flat region in a first clamped portion of thetransfixion pin and a second flat region in a second clamped portion ofthe transfixion pin, wherein the first flat region of the transfixionpin is grasped in a first clamping bolt and the second flat region ofthe transfixion pin is grasped by a second clamping bolt. In anembodiment, the apparatus further comprises a pin-holding apparatussuitable for holding a fixation pin for fixating the bone.

In another embodiment of the invention, a kit for fixation of boneincludes a Y-frame comprising a superior arm, an anterior arm, and aposterior arm, the arms having respective slots therein; a clampingbolt; a pin-holding assembly comprising a rocker nut or pin-holdingassembly that discretizes an angular position and comprises a rocker nutor pin-holding assembly that permits continuous adjustment, and shimwashers that can optionally be used in said pin-holding assembly. In anembodiment, some of the shim washers permit or can be used to permitcontinuous adjustment of a translational position, and the shim washersin a different orientation, or other shim washers, can be used to permitdiscrete adjustment of the translational position.

In another embodiment of the invention, a kit for fixation of boneincludes a superior arm, an anterior arm, a posterior arm, and a hub,wherein the superior arm, anterior arm and posterior arm are joinable tothe hub.

BRIEF DESCRIPTION OF THE ILLUSTRATIONS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

Embodiments of the invention are further described but are in no waylimited by the following illustrations:

FIG. 1 is a top perspective view of a Y-frame of an embodiment of theinvention;

FIG. 2 is a side view of the Y-frame of FIG. 1 ;

FIG. 3 is a top view of the Y-frame of FIG. 1 ;

FIG. 4 is an anterior view of the Y-frame of FIG. 1 ;

FIG. 5 is a posterior view of the Y-frame of FIG. 1 ;

FIG. 6 is a bottom view of the Y-frame of FIG. 1 ;

FIG. 7 is a top perspective view of a pin-holding assembly suitable foruse in the Y-frame of FIG. 1 ;

FIG. 8 is an exploded view of the pin-holding assembly of FIG. 7 ;

FIG. 9 is a top exploded perspective cross-sectional view of the yokeand the clamp of the pin-holding assembly, illustrating a wedgingaction;

FIG. 10 is a top perspective view of the clamp and the rocker arm,separated from each other, illustrating engagement of respective teethwith each other;

FIG. 11 is a bottom perspective view of a shim washer and a yoke,separated from each other, illustrating their interaction;

FIG. 12 is a partial perspective view of an arm having grooves on asurface, and its interaction with a shim washer;

FIG. 13 is a partial perspective view of an arm having countersinks, andits interaction with a shim washer;

FIG. 14 is a perspective view of the superior transfixion pin and itsclamping bolt;

FIG. 15 is a cross-sectional view of the superior transfixion pin andits clamping bolt;

FIG. 16 is a top perspective view of the Y-frame of FIG. 1 , togetherwith gripping hardware in each arm and a superior transfixion pin and ananterior fixation pin and a posterior fixation pin;

FIG. 17 is a top perspective exploded view of another embodiment of aY-frame having the ability to adjust the twist angles of one of thearms;

FIG. 18 is a top perspective view of another embodiment of a Y-framehaving separate arms, having the ability to adjust within a range, theangulation of the arms within the plane of the Y-frame;

FIG. 19 is a top perspective view of another embodiment of a Y-framehaving a hub and separate arms, having ability to adjust angulation ofthe arms within the plane of the Y-frame, with the possible angularpositions being discrete positions;

FIG. 20 is a top perspective view of a another embodiment of a Y-framehaving a hub and separate arms, having ability to adjust, continuouslywithin a range, the angulation of the arms within the plane of theY-frame, and also the ability to adjust the twist angle of individualarms with respect to a respective longitudinal axis of the individualarm;

FIG. 21 shows an embodiment having grooves on a surface of a sphericalhub and shows one arm with one type of groove-complementary feature.

FIG. 22 shows an embodiment having grooves on a surface of a sphericalhub and shows several arms with various groove-complementary features onthe hub-facing surface of the arms;

FIG. 23 is a top perspective view of a skeletal foot and ankleinstrumented according to an embodiment of the invention;

FIG. 24 is a side view corresponding to FIG. 23 ;

FIG. 25 is a top perspective view of a pair of Y-frames according to anembodiment of the invention, as connected by a superior transfixion pin;

FIG. 26 is a sectional view of FIG. 25 ;

FIG. 27 shows a transfixion pin that has a flat on it;

FIG. 28 shows the transfixion pin of FIG. 27 used in a configurationsuch that it applies a rotational constraint;

FIG. 29 shows the transfixion pin of FIG. 27 used in a configurationsuch that it does not apply a rotational constraint;

FIG. 30 shows a clamping bolt that does not apply a constraint on acertain degree of freedom of rotation;

FIG. 31 shows the clamping bolt of FIG. 30 in its interaction with thesuperior arm slot in the superior arm;

FIG. 32 shows a clamping bolt that is able to apply a constraint on acertain degree of freedom of rotation, and;

FIG. 33 shows the clamping bolt of FIG. 32 in its interaction with thesuperior arm slot in the superior arm.

DETAILED DESCRIPTION OF THE INVENTION

Directional and spatial anatomical terminology that may be used hereinis well known to those skilled in the art. For instance, the term“medial” typically means closer to the midline of the body, and“lateral” typically means farther from the midline of the body. Furtherterms, such as “proximal”, “distal”, “anterior”, “posterior”,“superior”, “inferior”, and other such terms shall have their common andordinary meanings in the art.

Basic Y-Frame

Referring now to FIGS. 1-6 , an embodiment of the invention comprises aY-frame 100. FIG. 1 is a perspective view. FIGS. 2-6 are, respectively,views from the side, top, anterior, posterior and bottom. In theembodiment that is shown in FIG. 1 , the Y-frame 100 is substantiallyrigid and the Y-frame 100 itself is non-adjustable. As illustrated,Y-frame 100 may have an axis 110 and an axis hole 150 as discussedherein. In an embodiment, the Y-frame has three arms, designated as asuperior arm 200, an anterior arm 300, and a posterior arm 400. Invarious embodiments, these arms are identical to each other, or the armsdiffer in length or other dimensions or other features.

In an embodiment, superior arm 200 has superior arm axis 210 generallyalong its lengthwise direction. In an embodiment, superior arm 200 hastherethrough a superior arm slot 220, extending generally along aportion of the length of superior arm 200, and generally parallel tosuperior arm axis 210. In an embodiment, superior arm slot 220 has asuperior arm slot plane 222 extending through the middle of superior armslot 220. In an embodiment, superior arm 200 has a superior arm end hole240, whose axis aligns with superior arm axis 210. In an embodiment,superior arm 200 has a superior arm side hole 250, whose axis isperpendicular to superior arm axis 210. Superior arm side hole 250 isillustrated as intersecting with superior arm slot 220. However, in analternate embodiment, the superior arm side hole 250 extends through thesolid uppermost portion of superior arm 200 and does not intersect withsuperior arm slot 220. In various embodiments, similar side holes andend holes are formed in the other arms 300, 400.

In an embodiment, anterior arm 300 has anterior arm axis 310 generallyalong its lengthwise direction. In an embodiment, anterior arm 300 hastherethrough an anterior arm slot 320, extending generally along aportion of the length of anterior arm 300. In an embodiment, anteriorarm slot 320 has an anterior arm slot plane 322 extending through themiddle of anterior arm slot 320.

In an embodiment, posterior arm 400 has a posterior arm axis 410generally along its lengthwise direction. In an embodiment, posteriorarm 400 has therethrough a posterior arm slot 420, extending generallyalong a portion of the length of posterior arm 400. In an embodiment,posterior arm slot 420 has a posterior arm slot plane 422 extendingthrough the middle of posterior arm slot 420. Posterior arm 400 is shownas having a posterior arm end hole 440.

In an embodiment, the arms 200, 300, 400 are rigidly joined to eachother at a central region 160. In various embodiments, superior arm slotplane 222, anterior arm slot plane 322 and posterior arm slot plane 422are coplanar with each other, or are parallel with each other, even ifnot coplanar. In an embodiment, axes 210, 310, 410 intersect with eachother at a common point in the central region of Y-frame 100. Asillustrated in FIG. 1 , all three of these axes 210, 310, 410 lie in acommon plane. In an embodiment, the respective angles between axes 210,310, 410 are chosen as a function of the intended use regardinganatomical features such as skeletal features. Superior arm 200,anterior arm 300 and posterior arm 400 can have any desired dimensionsas appropriate to the need. In various embodiments, the dimensions ofarms 200, 300, 400 are identical to each other, or the dimensions aredifferent from each other, if desired.

In an embodiment, slots 220, 320, 420 extend through surfaces ofrespective arms 200, 300, 400 that generally face another one ofrespective arms 200, 300, 400. In various embodiments, slots 220, 320,420 are of generally constant width (except near their ends), and aresuitable to receive mounting hardware, as described elsewhere herein. Invarious embodiments, slots 220, 320, 420 are identical to each other, orare different from each other, if desired.

Also illustrated is a central axis hole 150, formed through centralregion 160 (see FIGS. 1 and 2 ). In an embodiment, the central axis hole150 coincides with Y-frame axis 110 and passes through the intersectionpoint of superior arm axis 210, anterior arm axis 310 and posterior armaxis 410.

In various embodiments, anterior arm 300 and posterior arm 400 includeany variety of arm end holes and arm side holes similar to superior armend hole 240, and superior arm side hole 250, whether or not these areillustrated. In an embodiment, any such holes are useful for alignmentof various hardware, or for temporarily holding pins or othercomponents, or for other purposes as may be desired by a health careprovider.

In various embodiments, Y-frame 100 has still other features thatprovide an ability for Y-frame 100 to be connected to still otherhardware, such as other frames.

In an embodiment, Y-frame 100 is constructed of a radiopaque material,such as a metal. Alternatively, Y-frame 100 is constructed of aradiolucent material, such as a polymer (polyetheretherketone, carbonfiber, etc.). In some embodiments where Y-frame 100 is constructed of aradiolucent material, Y-frame 100 contains radiopaque markers in desiredplaces. In various embodiments, such radiopaque markers are pins orspheres of metal or a similar radiopaque material, and are press-fittedinto known places in Y-frame 100.

Pin-Holding Assembly

Reference is now made to FIG. 7 and FIG. 8 . In embodiments of theinvention, there may be provided a pin-holding assembly 500 that isattachable to any of superior arm 200, anterior arm 300 or posterior arm400 as desired. In an embodiment, pin-holding assembly 500 moveably andinsertably engages with slots 220, 320, 420. In an embodiment,pin-holding assembly 500 provides for the rigid attachment of a pin(such as a fixation pin 980 as illustrated or a transfixion pin) to anyof the arms 200, 300, 400, while allowing adjustability of theorientation and position of the pin prior to tightening of pin-holdingassembly 500. A single pin-holding assembly 500 is illustrated herein asbeing provided respectively on anterior arm 300 and on posterior arm400, although pin-holding assemblies 500 could be provided on any arm inany combination, and/or in any quantity.

In an embodiment, pin-holding assembly 500 comprises bolt 510, whichpasses through yoke 520. In an embodiment, bolt 510 is dimensioned suchthat its shaft 512 passes through slots 220, 320, 420 but its head 514does not pass through those slots.

In an embodiment, yoke 520 has a yoke axial bore 522, through whichshaft 512 of bolt 510 passes. In an embodiment, yoke 520 also has a yokecross bore 524, which intersects yoke axial bore 522 and is generallyperpendicular to yoke axial bore 522. In an embodiment, yoke cross bore524 has a circular shape in its lower region, but is illustrated ashaving a flat shape in its upper region. In an embodiment, yoke 520 has,on its external surface, a pair of opposed flats 521, which are parallelto each other and are suitable to be gripped by a wrench for purposes oftightening and untightening the connection, using bolt 510, of thepin-holding assembly 500 to arms 200, 300, 400.

In an embodiment, yoke 520 also has, in its upper region, an internaltaper 528. In an embodiment, internal taper 528 is a segment of aconical surface. Such configuration may help to achieve a wedge actionthat causes clamp 550 to grasp a pin. This is shown in particular detailin FIG. 9 .

In an embodiment, pin-holding assembly 500 comprises rocker nut 530. Inan embodiment, bolt 510 threads into rocker nut 530. In an embodiment,rocker nut 530 has threaded hole 532 therethrough suitable to engagewith bolt 510. In an embodiment, when tightened, bolt 510 urges rockernut 530 toward the head 514 of bolt 510 and toward whichever arm 200,300, 400 pin-holding assembly 500 is mounted on. In an embodiment, suchaction secures pin-holding assembly 500 onto respective arm 200, 300,400 and also secures clamp 550 and may secure a fixation pin 980 ortransfixion pin in clamp 550.

In some embodiments, pin-holding assembly 500 further comprises clamp550. In an embodiment, clamp 550 has therethrough a clamp cross-bore554. In some embodiments, yoke cross-bore 524, clamp cross-bore 554 androcker nut 530 are all shaped such that clamp 550 is allowed to rotatethrough a range of angles (around the axis of yoke cross-bore 524) butat the end of that range of angles, rotation is limited by thenon-circular portion of clamp cross-bore 554 bumping into rocker nut530. In one embodiment, clamp 550 has a central slot 556 that isgenerally perpendicular to clamp cross-bore 554, opening upwardly in theillustrated orientation, such that slot 556 divides clamp 550 into twohalves that are bendably connected to each other by the remainingnon-slotted portion of clamp 550. As a result, in an embodiment, the twosides of clamp 550 have some ability to flex toward or away from eachother so as to grasp a pin. In one embodiment, clamp 550 also hastherethrough a partial channel 560 that intersects slot 556 and ispartially defined by a concave shape in each of the two halves of clamp550, and is suitable to hold a fixation pin 980 or transfixion pin.

Prior to tightening, a) pin-holding assembly 500 can rotate around theaxis 591 of the bolt 510, as indicated at 592, b) fixation pin 908 canrotate around its own longitudinal axis, as indicated at 593, and cantranslate along its own longitudinal axis, as indicated at 594 and c)bolt 510 and pin-holding assembly 500 can slide in slot 420, asindicated at 595. In addition, rocker nut 530 allows rotation around theaxis 596 of yoke cross bore 524, as indicated at 597.

In one embodiment, clamp 550 has, on its exterior, an external taper558. In one embodiment, external taper 558 is conical. In oneembodiment, the conical shape corresponds to internal taper 528, whichis also conical. In one embodiment, external taper 558 cooperates withinternal taper 528 of yoke 520 to provide a wedging action that urgesthe two halves of clamp 550 toward each other to grasp a fixation pin ortransfixion pin. The conical nature of external taper 558 and internaltaper 528 allows bolt 510 to exert pulling force that creates a wedgeaction for any of a variety of angular orientations of clamp 550relative to rocker nut 530. This is particularly illustrated in FIG. 9 .

Referring now to FIG. 10 , in an embodiment, rocker nut 530 has anexterior surface that is generally shaped like a portion of a cylinder,such as a half-cylinder, with teeth 535 projecting from it. In oneembodiment, such teeth 535 project along the entire length of rocker nut530. In one embodiment (not shown), yoke cross-bore 524 is larger thanthe exterior of rocker nut 530 including its teeth 535, and the interiorof yoke cross-bore 524 is free of teeth. In one embodiment, clampcross-bore 554 comprises teeth 555 that are suitable to engage with theteeth 535 on the exterior surface of rocker nut 530. It is not necessarythat the angular spacing between adjacent teeth of one set of teeth beidentical to the angular spacing between teeth in the other set ofteeth. Rather, in an embodiment, it is simply desirable that the angularspacing of one set of teeth be an integer multiple of the angularspacing of the other set of teeth. As illustrated in FIG. 10 , thetooth-to-tooth angular spacing of teeth 555 on the clamp cross-hole 554is one-third of the tooth-to-tooth angular spacing of teeth 535 on therocker nut 530. As far as the extent along the axial direction of therocker nut 530, the axial extent of teeth 555 on the inside of clampcross-hole 554 need not be the same as the axial extent of teeth 535 onthe rocker nut 530. In regard to the angular extent of the toothedregions, the angular extent of the toothed region inside the clampcross-hole 554 does not have to be the same as (for example it could besmaller than) the angular extent of the toothed region on the rocker nut530. It can be understood that for small angular extent of eithertoothed region, in combination with appropriate tooth dimensions, it maybe possible to rotate rocker nut 530 within yoke cross-bore 524, afterseparating rocker nut 530 from clamp 550 generally along the lengthwisedirection of bolt 510. On the other hand, for larger angular extent ofboth toothed regions in combination with appropriate tooth dimensions,change of angular position of rocker nut 530 might only be possible bysliding rocker nut 530 out of yoke cross-bore 524 along the axialdirection of yoke cross-bore 524, rotating rocker nut 530 to a newangular orientation, and sliding rocker nut 530 back into yokecross-bore 524.

Furthermore, although illustrations show arrays of teeth 535 and teeth555, in some embodiments, that definition of angular position of clamp550 relative to rocker nut 530 could be accomplished if one of thosearrays of teeth were only a single-tooth suitable to engage the array ofteeth on the other component. Furthermore, in an embodiment, if thesurface of one of the components (rocker nut 530 and clamp cross-bore554) were smooth rather than toothed, even if the other component'ssurface remained toothed, there could be continuous adjustment ofangular position of clamp 550 relative to rocker nut 530 and yoke 520.

Referring now to FIGS. 7, 8 and 11 , in various embodiments, one or moreshim washers 570 are used to adjust overall elevation of the pin-holdingassembly 500 (or, more precisely, the location of the gripped pin in adirection perpendicular to the surface of arm 200, 300, 400). In variousembodiments, any desired number of shim washers 570 may be used, or noneat all. In various embodiments, shim washers 570 are identical or havevarious different thicknesses such as to permit both fine and coarseadjustment. In one embodiment, shim washers 570 are U-shaped having aslot 572, so that they can be slipped onto or off of the stack of shimwashers 570 without disassembling bolt 510 from rocker nut 530. In oneembodiment, shim washers 570 have a raised feature 574 on one surfaceand, on an opposed surface, a corresponding recessed feature 576suitable to nest with raised feature 574. The nesting features (raisedfeature 574 and recessed feature 576) of shim washers 570 areillustrated in FIG. 8 . In one embodiment, yoke 520 has on its underside(shim-washer-facing surface) a recessed feature 576 suitable to matewith raised feature 574 on shim washer 570. This is illustrated in FIG.11 . Raised feature 574 and recessed feature 576 are shown as beingaxisymmetric, but if desired they could have a more complicatednon-axisymmetric shape. In an embodiment, the interaction of raisedfeature 574 and recessed feature 576 helps to keep the stack of shimwashers 570 assembled during trial fitting operations. In oneembodiment, a bolt 510 is chosen whose length is appropriate for thenumber and dimensions of shim washers 570 used. In one embodiment, bolts510 of varying lengths are provided. In various embodiments, in order toaccommodate different lengths of bolt 510, the bolt-receiving threadedbore 532 through rocker nut 530 extends through the entirety of rockernut 530, and there is provided empty space inside yoke 520 above rockernut 530 in the indicated orientation. However, in an embodiment, abovethat empty space, sufficiently narrow space is provided so that bolt 510cannot actually touch a pin (fixation pin 980 or transfixion pin 1000)that is grasped by pin-holding assembly 500. Such touching, if it wereto occur, might act undesirably to urge a pin 980 or 1000 out of itsgrasped arrangement within clamp 550.

As illustrated in FIGS. 1-6 , the slots 320, 420, 520 are of uniformcross-section along their lengths, except near their curved ends. Asalso illustrated in these Figures, the pin-holding assembly 500 and thebolt 510 interact with the slots 220, 320, 420 in such a way that thetranslational position of pin-holding assembly 500 in slots 220, 320,420 is chosen from a continuous range. However, there also are otherpossibilities involving discrete translational positions.

Referring now to FIG. 12 , in some embodiments, any one or more of armsurfaces adjacent to slots 220, 320, 420 include ridges 479 that arespaced at uniform intervals, and such ridges 479 encourage or requirethe pin-holding assembly 500, when tightened, to occupy one of thepositions defined by the ridges 479. For example, in one embodiment,shim washers 570 have, on their undersides, ridges 579 that arecomplementary to the ridges 479 on the arms 200, 300, 400. If the shimwasher 570 has an appropriate angular orientation, the ridges 579 on theshim washer 570 can engage with the ridges 479 on the surface of the armso, as to define discrete translational positions. If the shim washer570 has a different angular orientation, such as an orientation wherethe respective ridges 479, 579 are oriented approximately perpendicularto each other, ridges 579 and ridges 479 will not engage with each otherand continuous adjustment of translational position will be possible. Ofcourse, depending on the wishes of the user, it would also be possibleto use a shim washer 570 having a smooth underside, which would providecontinuous adjustment of translational position even if there are ridges479 on the arm 200, 300, 400.

FIG. 12 shows at 571 an engaging orientation for washer 570 and furthershows at 573 a non-engaging orientation for washer 570.

Similar considerations apply to yoke 520 and its underside surface. Ifno shim washers 570 are used, the underside surface of yoke 520 contactsa surface of arms 200, 300, 400 in various embodiments. In anembodiment, such underside surface of yoke 520 could be either smooth orgrooved. If grooved, in an embodiment, such surface could result in aconstraint against rotation of pin-holding assembly 500 around the axisof bolt 510, in addition to constraining the translational position todiscrete locations along the length of slot 220, 320, 420.

Referring now to FIG. 13 , in another embodiment, arms and slots such asslots 220, 320, 420 have discrete features along them in the form ofdished shapes such as countersinks 580, and the underside of shimwashers 570 or of yoke 520 has features 582 complementary to thecountersinks 580. In an embodiment, choice between discrete andcontinuous positioning could be made by the choice of using shim washers570 that either have a flat bottom (which would avoid interaction withthe countersinks 580) or have on their bottom a protrusion 582 thatengages with the countersinks 580. For engaging with countersinks 580,in one embodiment, the protrusions 582 are conical. In FIG. 13 , one ofthe shim washers 570 is illustrated as having a conical protrusion 582around a full circumference of a cone (except where the washer 570 isslotted by slot 572). In an embodiment, such a protrusion 582 wouldengage a countersink 580 for any angular orientation of shim washer 570.As is also illustrated in FIG. 13 , it is also possible that a shimwasher 570 could have a conical protrusion 582 that is abbreviated fromtwo opposed sides, such that the remaining conical protrusion 582 has awidth W. For such a shim washer 570, in an embodiment, if the shimwasher 570 is oriented in one angular position (with respect to the axisof the hole through shim washer 570), the protrusion 582 would engagewith the countersink 580. For the same shim washer 570, in anembodiment, assuming that the remaining width W of the protrusion 582 isnarrower than the width of slot 220, 320, 420, the protrusion 582 canreside within the slot 220, 230, 240 and avoid engaging the countersink580. Such a situation, in an embodiment, would provide continuousadjustability of the translational position of pin-holding assembly 500along arm 200, 300, 400.

In an embodiment, a pin-holding assembly 500 can be used to hold eithera fixation pin 980 or a transfixion pin 1000. The use of a pin-holdingassembly 500 with superior arm 200 is not illustrated, although in anembodiment a pin-holding assembly 500 could be so used if desired.

In an embodiment, pin-holding assembly 500 may provide at least thefollowing degrees of adjustability. This adjustability can be providedwith respect to arms 200, 300, 400

-   -   In translation along the length of arm 200, 300, 400, it is        possible to adjust and then lock the position of pin-holding        assembly 500 along the linear direction of slots 220, 320, 420.        In some embodiments, this adjustment is illustrated as being        continuous.    -   In translation perpendicular to the surface of arm 200, 300,        400, the position of pin-holding assembly 500 can be adjusted        and then locked by the selection and use of shim washers 570.        This adjustment can be discrete because of the use of discrete        shim washers 570.    -   In a third translational direction, the position of pin 980 can        be adjusted and then locked by sliding pin 980 along the length        direction of pin 980, within clamp 550.    -   In regard to rotation around the axis of bolt 510, the        orientation of pin 980 can be adjusted and then locked by        rotating yoke 520 around the axis of bolt 510. As illustrated in        FIG. 7 , this adjustment is continuous.    -   In regard to rotation around the axis of yoke cross-bore 524,        the orientation of pin 980 can be adjusted and then locked by        rotating clamp 550 with respect to rocker nut 530 and yoke 520.        It is illustrated that this adjustment is in discrete steps, but        it is described that continuous adjustment also could be        achieved.    -   In regard to rotation around the axis of pin 980, it is possible        for pin 980 to be rotated and then locked with respect to that        axis, but in practice this may be unnecessary or insignificant        because of the axisymmetric nature of the overall features of        pin 980.        Clamping Bolt

FIGS. 14-15 illustrate the use of a clamping bolt 700 to secure atransfixion pin 1000 to superior arm 200 of Y-frame 100. In oneembodiment, this configuration and the use of clamping bolt 700 providesfewer degrees of adjustability (i.e., more degrees of constraint) thanare provided by pin-holding assembly 500. In FIG. 15 , clamping bolt 700is shown engaging with superior arm slot 220 such that clamping bolt 700urges the transfixion pin 1000 directly into contact with a flat surfaceof superior arm 200. In an embodiment, clamping bolt 700 engages withnut 710. It can be understood that if desired, instead of clamping atransfixion pin 1000, clamping bolt 700 could be used to clamp afixation pin (not illustrated). In various embodiments, the pin-holdingassembly 500 and clamping bolt 700 are used at the same time, asdiscussed below and as illustrated in FIGS. 23 and 24 .

Bolt 700 may provide at least the following degrees of adjustability.This adjustability can be provided with respect to arms 200, 300, 400although it is only illustrated with superior arm 200.

-   -   In translation along the length of arm 200, 300, 400, it is        possible to adjust and then lock the position of pin-holding        assembly 500 along the linear direction of slots 220, 320, 420.        This adjustment is illustrated as being continuous.    -   Translational adjustment perpendicular to the surface of arm        200, 300, 400, adjustment is illustrated as not being possible;        transfixion pin 1000 is constrained to touch the surface of arm        200, 300, 400.    -   In another translational direction, along the longitudinal        direction of transfixion pin 1000, the position of pin 1000 can        be adjusted and then locked by sliding transfixion pin 1000        along the length direction of transfixion pin 1000, within        clamping bolt 700.    -   In regard to rotation around the axis of the arm (such as axis        210 of arm 200), transfixion pin 1000 is constrained to be in        contact with the flat surface of the arm. This eliminates a        degree of freedom of adjustment that roughly corresponds to the        degree of freedom of rotation that, in pin-holding assembly 500,        was provided by rotation of clamp 550 with respect to rocker nut        530.    -   In regard to rotation around the axis of clamping bolt 700, as        illustrated in FIGS. 14-15 , adjustment is permitted of this        angular position. This roughly corresponds to the degree of        freedom of rotation that, in pin-holding assembly 500, was        provided by rotation of pin-holding assembly 500 around the axis        of bolt 510. However, elsewhere herein there is described an        alternative design of clamping bolt 700 that imposes a        constraint in this regard.    -   In regard to rotation around the axis of transfixion 1000, it is        possible for transfixion pin 1000 to be rotated and then locked        with respect to that axis, but in practice this may be        unnecessary or insignificant because of the axisymmetric nature        of the overall features of transfixion pin 1000.

FIG. 16 illustrates a Y-frame 100 in combination with mounting hardwareon each arm 200, 300, 400. In particular, FIG. 16 shows a transfixionpin 1000 attached to superior arm 200 by clamping bolt 700, and fixationpins 980 attached to anterior arm 300 and posterior arm 400 bypin-holding assemblies 500. It can be understood that in embodiments itis possible to attach either a fixation pin 980 or a transfixion pin1000 to any of arms 200, 300, 400 using either a pin-holding assembly500 or a clamping bolt 700. Any quantity of such transfixion pins 1000,fixation pins 980, and clamping bolts 700 and pin-holding assemblies 500can be used on any arm 200, 300, 400, as may be desirable for the needsof a particular patient.

Y-Frame Having Arms that Permit Rotation Around Long Axis of RespectiveArm

In embodiments illustrated in FIGS. 1-6 , the arms 200, 300, 400 aresubstantially rigidly connected to each other, having fixed positionsrelative to each other. In another embodiment of the invention, the arms200, 300, 400 allow adjustment of an angle that can be referred toherein as an arm twist angle, and such motion can be referred to as armtwisting. This arm twist angle can refer to rotation around of oneportion of the arm 200, 300, 400, with respect to another portion of thesame arm or with respect to a central region 116 of the Y-frame 100.Such rotation can be rotation around an axis such as superior arm axis210, anterior arm axis 310, posterior arm axis 410.

Referring now to FIG. 17 , there is shown an embodiment of the Y-frame100 that allows adjustment of arm-twist angle independent of any otheradjustment. Such adjustment may be provided by twisting pivot 496.Twisting pivot 496 is shown as being located between slot 420 and thecentral region of Y-frame 100. In an embodiment, there may be provided alocking or tightening mechanism for locking twisting pivot 496. In oneembodiment, detents are also provided in this rotation, if desired.

Y-Frame Having Arms that can Angulate with Respect to Each Other

In further embodiments of the invention, it is possible to provideangular adjustability of arms 200, 300, 400 in an angular direction thatis within the plane of arms 200, 300, 400 (assuming that axes 210, 310,410 of arms 200 300, 400 are coplanar). These angles can be referred toherein as arm rotational angles and the motion can be referred to hereinas angulation.

For example, as illustrated in FIG. 18 , in an embodiment there isprovided a common hinge such that arms 200, 300, 400 all rotate aroundY-frame axis 110. As illustrated, superior arm 200 has superior armfinger projections 292, anterior arm 300 has anterior arm fingerprojections 392 and posterior arm 400 has posterior arm fingerprojections 492. In an embodiment, these finger projections 292, 392,492 have respective holes therethrough that align with each other, and ahinge pin 900 is provided that fits through those holes to create thehinge.

In various embodiments, finger projections 292, 392, 492 fit among eachother with a close but freely moving fit, and finger projections 292,392, 492 have a desired degree of ability to deflect relative to eachother along the axis of hinge pin 900. Furthermore, in an embodimentthere may be provided a clamping device 910 such as a cam clamp that issuitable to exert force urging the finger projections 292, 392, 492 intocontact with each other so as to lock the relative angular positions ofarms 200, 300, 400.

For example, in an embodiment, the clamping device 910 creates tensileforce in hinge pin 900 and that tensile force is used to urge all of thefinger projections 292, 392, 492 compressively into contact with eachother. In one embodiment, finger projections 292, 392, 492 are designedwith an appropriate amount of flexibility so as to allow enoughdeflection to achieve the desired locking upon application of force byclamping device 910. Such contact is frictional contact in oneembodiment. Such contact may be enhanced with surface roughness asdesired in one embodiment. In one embodiment, clamping device 910 is orincludes a cam with a handle to cause rotation of the cam in order tourge finger projections 292, 392, 492 into contact with each other.

The arrangement illustrated in FIG. 18 is capable of continuousadjustment over a range of angles between arms 200, 300, 400. As analternative, in an embodiment, the angles that are permitted or areallowed or accessible are certain discrete angles. This can be achievedwith the illustrated hinge arrangement if appropriate surfaces of fingerprojections 292, 392, 492 that face each other have grooves orserrations, such radially oriented serrations centered at the hinge axisof hinge pin 900. Thus, when the arms 200, 300, 400 are not locked toeach other, there is ability of the finger projections 292, 392, 492 torotate relative to one another around the axis of hinge pin 900, so asto allow relative rotation of the arms 200, 300, 400. In alternateembodiments, there is an incentive for the arms 200, 300, 400 to settleinto certain discrete angular positions. In one embodiment, thesediscrete angular positions are spaced at equal angular intervals. In oneembodiment, spring loading along the axis of the hinge pin 900 is usedto govern the ease or difficulty of moving among the permitted angularpositions, creating detents for the rotation.

Apparatus Having Interchangeably Connectable Hub and Arms

FIGS. 19-22 illustrate further embodiments of the Y-frame that includeother ways of achieving angular adjustment such as angulation orarm-twisting or both is to have a hub 800 such that arms 200, 300, 400interact with a surface of the hub 800 and are joinable to hub 800. Invarious embodiments, the joining comprises respective locking screws orother mechanism through the sidewall 810 of the hub 800. The sidewall810 of hub 800 can have appropriate slots for respective locking screwsto pass through. The dimensional relationship between locking screws andslots can provide constraint on motion as desired.

With the exception of grooves or similar features, in variousembodiments, the surface of hub 800 is generally cylindrical orpolygonal-prismatic (as shown in FIG. 19 ) or generally spherical (asshown in FIG. 20 ). In an embodiment, a generally cylindrical orpolygonal prismatic hub 800 could prevent out-of-plane alignment of thevarious arms 200, 300, 400 and could require the arms 200, 300, 400 tobe coplanar. In an embodiment, a constraint of the allowable rotationalangles to discrete intervals could be achieved with polygonal facets onthe surface of the hub 800. This is shown in FIG. 19 . Aless-constrained situation can be achieved with an externally sphericalhub as shown in FIG. 20 .

As illustrated in FIGS. 21-22 , the surface of the hub 800 can havegrooves therein, in further embodiments of the Y-frame. In oneembodiment, grooves are parallel to other similar grooves. In oneembodiment, there are two different groups of grooves 830A, 830B thatintersect each other generally perpendicularly. As one example, in suchan embodiment, if the grooves 830A are in the plane of the rotationalangles, and if the arms 200, 300, 400 engage with the grooves 830A, thegrooves 830A may permit continuous angular motion of arms 200, 300, 400among various rotational angles. At the same time, in such anembodiment, such grooves 830A may provide some degree of constraint withregard to other degrees of motion (such as the arm twist angle ofrespective arms 200, 300, 400). In such an embodiment, if grooves 830Bare perpendicular to the plane of the rotational angles, and if the armsengage with the grooves 830B, the grooves 830B may discretize theachievable rotational angles. FIG. 22 shows one of the arms interactingwith one set of grooves 830A based on a groove-complementary feature840A oriented in one direction, and another of the arms interacting withthe other grooves set of grooves 830B oriented in another direction withanother appropriately oriented groove-complementary feature 840B.

In various embodiments, the hub-facing surface of the arms 200, 300, 400has groove-complementary features such as teeth. In various embodiments,these features extend in one direction, or in two directions, or thehub-facing surface could be smooth and non-interacting with the grooves.

In various embodiments, discrete definition or adjustment of the angularpositions can be achieved with the presence of grooves 830A, 830B on thesurface of hub 800 and groove-complementary features 840A, 840B on theends of arms 200, 300, 400. In various embodiments, if it is desired tohave continuous rather than discrete adjustment of rotational angle,either situation is possible depending on the nature of the hub-facingsurface of the arms. In various embodiments, different arms havedifferent such characteristics if desired.

Certain reference directions are further shown in FIG. 16 , includingsagittal plane 580, coronal plane 581, superior-inferior (vertical)direction 582, medial-lateral direction 583, and anterior-posteriordirection 584.

Additional Y-Frame, and Application to Foot

In an embodiment of the invention, a first Y-frame 100 can be usedtogether with a second Y-frame 100′ on the opposite side of an extremitysuch as a foot. As illustrated in FIGS. 23 and 24 , the Y-frame 100 onone side of the foot is identical to the Y-frame 100′ on the other sideof the foot, although if desired the two Y-frames 100, 100′ could differfrom each other in some way. Pins such as fixation pins 980 ortransfixion pins 1000 can enter the extremity from both sides of theextremity and can join to respective Y-frames 100, 100′.

FIGS. 23-24 illustrate application of embodiments of the invention to afoot. FIG. 24 is a side view of FIG. 23 . As illustrated, in the Y-frame100, the orientation of arms 200, 300, 400 with respect to each other issuch that the superior arm 200 roughly aligns with the patient's leg,the anterior arm 300 roughly aligns with the forward part of the foot,and the posterior arm 400 roughly aligns with the heel of the foot. Inan embodiment, the extent and positions of slots 220, 320, 420correspond to locations of likely interest for placement of pins forfixation of particular bones in the foot. In FIGS. 23-24 , all three ofthe illustrated pins are transfixion pins 1000. In an embodiment, one ofthe transfixion pins 1000 is held by clamping bolt 700, and two othersare held by pin-holding assemblies 500. This is a slightly different useof pins, compared to what is illustrated in FIG. 16 . In general, anytype of pin (fixation pin 980 or transfixion pin 1000) can be used witheither type of support (pin-holding assembly 500 or clamping bolt 700)on any arm (200, 300, 400).

Relative Geometric Orientation of Respective Y-Frames

Reference is now made to FIGS. 25-33 , in which the fixation apparatuscontains two identical Y-frames 100, 100′ of the type illustrated inFIGS. 1-6 .

In embodiments of the invention, there may be provided various geometricconstraints among certain components. In some embodiments there is atransfixion pin 1000 extending between two Y-frames 100, 100′ andrigidly attached to each of the Y-frames 100, 100′.

A transfixion pin 1000 proceeds, as one continuous pin, through a boneand out through the skin on each of two opposed sides of an extremity.In an embodiment, the external portions of a transfixion pin 1000 areengaged with fixation hardware at both ends thereof. In an embodiment, atransfixion pin 1000 extends from one Y-frame 100, into the extremity,through a bone, out of the extremity, and into another Y-frame 100′. Incontrast, in an embodiment, a fixation pin 980 (see FIGS. 7 and 8 )enters the extremity only once and extends into a bone but does not exitthe extremity. In an embodiment, a fixation pin 980 is supported byhardware only at one of its ends.

In an embodiment, if a transfixion pin 1000 is axisymmetric at both ofits gripping ends, it can permit a range of angular orientations of thetwo Y-frames 100, 100′ relative to each other around the longitudinalaxis of the transfixion pin 1000. Such a transfixion pin 1000 isillustrated in FIG. 25 and in FIG. 26 , which is a section of FIG. 25 .On the other hand, as illustrated in FIGS. 27-29 , if a transfixion pin1000 is non-axisymmetric at both of its gripping ends, it can serve todefine the relative angular orientation of the two Y-frames 100, 100′around the longitudinal axis of the transfixion pin 1000. In FIG. 27 ,it is illustrated that the transfixion pin 1000 can have a flat 1010 atone end, and in an embodiment transfixion pin 1000 can have another flat1010 at the other end, with the two flats being coplanar with eachother.

In an embodiment, during use, a transfixion pin 1000 having such flats1010 could be used in either of two ways. If the transfixion pin 1000 ismounted as illustrated in FIG. 28 such that its flat 1010 abuts againsta flat surface of an arm such as superior arm 200, then transfixion pin1000 can impose an angular constraint defining a relative orientation ofthe two Y-frames 100. Alternatively, in an embodiment, the sametransfixion pin 1000 could be installed as illustrated in FIG. 29 suchthat its round surface bears against the flat surface of the arm such assuperior arm 200, In such a situation, there would not be any constraintimposed on the relative orientation of one Y-frame 100 and the otherY-frame 100′ with respect to rotation around the longitudinal axis oftransfixion pin 1000.

Another type of geometric constraint is illustrated in FIGS. 30-33 foran embodiment. FIG. 30 shows a clamping bolt 700 such that the shaft 708of the clamping bolt 700, where the clamping bolt 700 passes throughslot 320, is round. FIG. 31 shows that the roundness of the shaft 708 ofthe clamping bolt 700 allows rotation of Y-frame 100 around the axis ofthe shaft 708 of clamping bolt 700, such that the overall plane of oneY-frame 100 and the overall plane of the other Y-frame 100′ can beeither parallel to each other or non-parallel, whichever is desired.

In an embodiment, it is also possible that this interaction can bedesigned such as to constrain that the plane of one Y-frame 100 and theplane of the other Y-frame 100′ be parallel to each other. For example,this interaction can be such that the shaft 708 of a clamping bolt 700can have a geometric relationship with the slot 220 such that theclamping bolt 700 is prevented from rotating about the lengthwise axisof shaft 708 within the slot 220. FIG. 32 shows a clamping bolt 700 suchthat the shaft 708 of the clamping bolt 700 is racetrack-shaped incross-section. FIG. 33 shows that the racetrack-shaped shaft 708 ofclamping bolt 700 has external flat-to-flat dimensions that areclose-fitting with the dimensions of internal surface or edges of slot220 and therefore shaft 708 interacts with the internal surface or edgesof slot 220 so as to create the constraint. A racetrack-shapedcross-section is considered to be a shape that has two parallel sides incombination with semicircles at each end. In other embodiments, thereare provided other similar cross-sectional shapes, such asrounded-rectangle, or an oval or elliptical shape or still otherelongated shapes. A cross-sectional shape that has some straight sides,and is closely-fitting with slot 220, might provide more effectiveconstraint than a cross-sectional shape lacking such straight sides. Insuch embodiments, the non-illustrated end of shaft 708 that accepts nut710 could be designed similarly to what is illustrated in FIGS. 25-31 .

Other design features are also possible to constrain the clamping bolt700 so as to prevent it from rotating about its own lengthwise axiswithin the slot 320. For example, the clamping bolt 700 could have afeature that interacts with an external feature of an arm such as arm200, or could have a feature that interacts with yet some other featureof an arm such as arm 200.

Kit

A kit according to an embodiment of the invention, contains a solidY-frame 100, or some form of Y-frames not disassemblable by the user,together with fixation hardware. Various embodiments of the kit compriseat least some, or all, of the following items:

Two or more Y-frames 100, 100′

Pin-holding assembly 500 (various assemblies or various rocker nuts 530)

Various shim washers 570 (thicknesses, surface shape)

Various bolts 510

Clamping bolt 700 (various)

Fixation pins 980

Transfixion pins 1000 (both round and flatted varieties)

In such a kit, if one wants to change the continuous/discrete rotationalangle properties regarding orientation of a pin, one could substitutethe appropriate rocker nut 530 in a pin-holding assembly 500.Alternatively, one could substitute an entire pin-holding assembly 500.If one wants to change the continuous/discrete translational properties,assuming that the arms have appropriate features, one can reorient orsubstitute shim washer 570. One could change a constraint of relativeorientation of two Y-frames by choice of clamp bolt 700. One couldchange a constraint of relative orientation of two Y-frames by choice ofor orientation of transfixion pin 1000.

In another embodiment of the kit, the Y-frames are themselvesassemblable by the user from sub-components, which can be assembled bythe user into Y-frames as desired. Various embodiments of the kitcomprise at least some, or all, of the following:

-   -   At least two hubs 800, having various groove combinations (hubs        may be generally cylindrical exterior or generally spherical        exterior)    -   At least three arms for each of at least two Y-frames; arms may        have various designs of groove-complementary features    -   Bolts for assembling hubs and arms    -   Shim washers 570 of identical or assorted different thicknesses    -   Pin-holding assemblies 500 (various)

In an embodiment, a kit of this type could contain various hubs 800having different directions of grooves or combinations of directions ofgrooves 830A, 830B. In an embodiment, there are provided arms 200, 300,400 that have various types of hub-facing surfaces such as grooved in asingle direction, grooved in multiple directions, or ungrooved. Each ofthese would define different degrees of engagement with the hub 800.

In an embodiment, for example, a hub 800 having a spherical exteriorwith grooves 830A, 830B in two mutually perpendicular orientations,depending on what geometry of hub-facing surface engages with it, couldpermit discrete angulation in one plane (if the hub-facing surface hasgroove-complementary features along one direction) with no arm twistingallowed; or it could permit continuous angulation in one plane (if thehub-facing surface has groove-complementary features along the otherdirection) with no arm twisting allowed, or it could provide continuousangulation in one plane (if the hub-facing surface is smooth) combinedwith arm twisting being allowed.

In an embodiment, arms 200, 300, 400 can be provided withgroove-complementary features 840A, 840B that extend in one direction,or extend in two generally perpendicular directions, or arms can beprovided with smooth hub-facing surfaces that do not engage grooves830A, 830B in the hub 800 at all.

In yet another embodiment, in which the arms 200, 300, 400 can be chosenand assembled by the user, multiple versions of arms 200, 300, 400 canbe provided so that the user can choose which arms he or she wishes tocombine to assemble the Y-frame 100.

Methods of Use

Embodiments of the invention can also comprise a method of use of thedescribed apparatus.

In an embodiment, during use, a transfixion pin 1000 having such flats1010 could be used in either of two ways. If the transfixion pin 1000 ismounted as illustrated in FIG. 28 such that its flat 1010 abuts againsta flat surface of an arm such as superior arm 200, then transfixion pin1000 can impose an angular constraint defining a relative orientation ofthe two Y-frames 100. The gap between superior arm 200 and clamp bolt700 is indicated at 701. Alternatively, in an embodiment, the sametransfixion pin 1000 could be installed as illustrated in FIG. 29 suchthat its round surface bears against the flat surface of the arm such assuperior arm 200. In such a situation, there would not be any constraintimposed on the relative orientation of one Y-frame 100 and the otherY-frame 100′ with respect to rotation around the longitudinal axis oftransfixion pin 1000. In this situation, gap 701 is somewhat wider thanwhen there is a constraint.

Another type of geometric constraint is illustrated in FIGS. 30-33 foran embodiment. FIG. 30 shows a clamping bolt 700 such that the shaft 708of the clamping bolt 700, where the clamping bolt 700 passes throughslot 320, is round. FIG. 31 , depicting a situation where constraint isnot applied, shows that the roundness of the shaft 708 of the clampingbolt 700 allows rotation of Y-frame 100 around the axis of the shaft 708of clamping bolt 700, such that the overall plane of one Y-frame 100 andthe overall plane of the other Y-frame 100′ can be either parallel toeach other or non-parallel, whichever is desired.

In an embodiment, it is also possible that this interaction can bedesigned such as to constrain that the plane of one Y-frame 100 and theplane of the other Y-frame 100′ be parallel to each other. For example,this interaction can be such that the shaft 708 of a clamping bolt 700can have a geometric relationship with the slot 220 such that theclamping bolt 700 is prevented from rotating about the lengthwise axisof shaft 708 within the slot 220. FIG. 32 shows a clamping bolt 700 suchthat the shaft 708 of the clamping bolt 700 is racetrack-shaped incross-section. FIG. 33 , depicting a case where constraint is applied,shows that the racetrack-shaped shaft 708 of clamping bolt 700 hasexternal flat-to-flat dimensions that are close-fitting with thedimensions of internal surface or edges of slot 220 and therefore shaft708 interacts with the internal surface or edges of slot 220 so as tocreate the constraint. A racetrack-shaped cross-section is considered tobe a shape that has two parallel sides in combination with semicirclesat each end. In other embodiments, there are provided other similarcross-sectional shapes, such as rounded-rectangle, or an oval orelliptical shape or still other elongated shapes. A cross-sectionalshape that has some straight sides, and is closely-fitting with slot220, might provide more effective constraint than a cross-sectionalshape lacking such straight sides. In such embodiments, thenon-illustrated end of shaft 708 that accepts nut 710 could be designedsimilarly to what is illustrated in FIGS. 25-31 .

In an embodiment, if apparatus includes provision for arm-twistingrotational adjustment or for angulation of arms relative to each other,adjustment of either of these geometric variables could be made at thetime of use.

In an embodiment, if components are provided in the form of a hub 800(or multiple hubs) and arms that are connectable to the hub 800, choicescould be made at the time of use as to which arms are connected to a hub800, and in what orientation.

In an embodiment, if the apparatus includes a transfixion pin 1000 thatcontains flats 1010 on it, the transfixion pin 1000 could be used ineither a constraining or a non-constraining mode depending on therotational position of the transfixion pin 1000 around the longitudinalaxis of the transfixion pin 1000. This decision can be made at the timeof use.

In an embodiment, as described herein, it is possible that a oneclamping bolt 700 could be provided for use in a constraining mode andanother clamping bolt 700 could be provided for use in anon-constraining mode. The choice could be made at the time of use. Inan embodiment it could also be possible, depending on the design of theclamping bolt 700 and associated features of the arms 200, 300, 400, touse a single clamping bolt 700 in either mode depending on how theclamping bolt 700 is installed such as with respect to angle around thelongitudinal axis of the shaft 708 of the clamping bolt 700.

Further Embodiments and Modifications

As illustrated herein, where two Y-frames 100, 100′ are shown, theY-frames 100, 100′ on opposite sides of the foot are shown as beingidentical to each other (see FIG. 23 ). However, if desired, inalternate embodiments, the Y-frames 100, 100′ could differ from eachother in any one or more of dimensions or features described herein, orin other dimensions or features.

Although illustrations herein show the clamping bolt 700 on the superiorarm 200 and the pin-holding assembly 500 on the anterior arm 300 andposterior arm 400, it is possible for the clamping bolt 700 to be usedon any arm 200, 300, 400. Similarly, the pin-holding assembly 500 couldbe used on any arm 200, 300, 400. In illustrations, a transfixion pin1000 is shown being grasped by a clamping bolt 700 and fixation pins 980are shown being grasped by a pin-holding assembly 500. However, it is tobe understood that either a transfixion pin 1000 or a fixation pin 980can be grasped by either a clamping bolt 700 or a pin-holding assembly500. Transfixion pins 1000 could be used on any arm 200, 300, 400, andfixation pins 980 could be used on any arm 200, 300, 400, in anycombination and in any quantity.

In illustrations, arm-twisting rotational joints 496 are shown on onearm 400, but it can be understood that such arm-twisting rotationaljoints 496 may be provided on whatever arms may be desired.

In illustrations of the pin-holding assembly 500, it is shown that thebolt 510 both attaches the pin-holding assembly 500 to the arm andtightens the clamp 550 around the pin. In an embodiment, it would bepossible to design the pin-holding assembly 500 such that one bolt 510anchors the pin-holding assembly 500 to the arm and a different boltcauses tightening of the clamp around the pin.

In an embodiment, there can be provided additional features on theY-frames 100, 100′, such as for interfacing with still other mechanicalcomponents for fixation or for other purposes.

In an embodiment, the arms 200, 300, 400 of the Y-frames 100, 100′ aremarked with dimensional scales or other indicators that may be usefulfor clinical purposes.

The described apparatus is shown for use on a human foot, but it shouldbe understood that the described apparatus could also be used on otherparts of the body.

In general, any combination of disclosed features, components andmethods described herein is possible. Steps of a method can be performedin any order that is physically possible.

All cited references are incorporated by reference herein.

Although embodiments have been disclosed, it is not desired to belimited thereby. Rather, the scope should be determined only by theappended claims.

What is claimed is:
 1. An apparatus for fixating at least one bone, saidapparatus comprising: a frame comprising a superior arm, an anterior armand a posterior arm, said superior arm, anterior arm and posterior armextending outwardly in respective different directions from a centralregion, said superior arm having a superior arm axis extending generallyalong a lengthwise direction of said superior arm through said centralregion, said superior arm having therethrough a superior arm slotextending generally along at least a portion of a length of saidsuperior arm and being generally aligned with said superior arm axis,said anterior arm having an anterior arm axis extending generally alonga lengthwise direction of said anterior arm through said central region,said anterior arm having therethrough an anterior arm slot extendinggenerally along at least a portion of a length of said anterior arm andbeing generally aligned with said anterior arm axis, said posterior armhaving a posterior arm axis extending generally along a lengthwisedirection of said posterior arm through said central region, saidposterior arm having therethrough a posterior arm slot extendinggenerally along at least a portion of a length of said posterior arm andbeing generally aligned with said posterior arm axis, wherein none ofsaid superior arm axis, said anterior arm axis and said posterior armaxis are collinear with each other, and wherein each of said slots isconfigured to receive mounting hardware that is a) mountable on saidarms through respective ones of said slots, b) able to occupy aplurality of translational positions along said slots, and c) able tohold at least one bone-fixating pin.
 2. The apparatus of claim 1,wherein said superior arm slot, said anterior arm slot and saidposterior arm slot define respective arm slot planes that are allsubstantially coplanar with each other and that extend through saidsuperior arm slot, said anterior arm slot and said posterior arm slot,respectively.
 3. The apparatus of claim 2, wherein at least one of saidarms comprises a surface that is substantially flat and substantiallyperpendicular to its respective arm slot plane, and wherein the slotextending through said at least one arm extends through saidsubstantially flat surface.
 4. The apparatus of claim 1 furthercomprising mounting hardware which comprises at least one pin-holdingassembly that is capable of holding a pin at a plurality of angularpositions around a first axis of rotation and is capable of holding saidpin at a plurality of angular positions around a second axis of rotationthat is different from said first axis of rotation, neither of said axesof rotation being a longitudinal axis of said pin.
 5. The apparatus ofclaim 1 further comprising mounting hardware which comprises at leastone pin-holding assembly that is capable of holding a pin at a pluralityof angular positions around a first axis of rotation, wherein each ofsaid angular positions is only permitted to be one of a plurality ofdiscrete angular positions.
 6. The apparatus of claim 1, wherein one ofsaid arms comprises a flat surface and wherein said apparatus furthercomprises mounting hardware comprising at least one clamping bolt thatis capable of clamping a pin directly against said flat surface.
 7. Theapparatus of claim 1 further comprising mounting hardware whichcomprises a pin-holding assembly and a clamping bolt, wherein saidpin-holding assembly provides more degrees of freedom for positioning arespective pin than does said clamping bolt.
 8. The apparatus of claim1, further comprising mounting hardware that, in a first direction oftranslation, allows continuous adjustment of the position of said pin,and that, in a second direction of translation different from said firstdirection of translation, allows adjustment in discrete steps of theposition of said pin.
 9. The apparatus of claim 1, further comprisingmounting hardware that, in rotation about a first axis of rotation,allows continuous adjustment of the position of said pin, and inrotation about a second axis of rotation that is different from saidfirst axis of rotation, allows adjustment in discrete steps of theposition of said pin.
 10. The apparatus of claim 1 further comprisingmounting hardware which comprises first pin fixation hardware attachableto said arms and second pin fixation hardware attachable to said arms,wherein said first pin fixation hardware and said second pin fixationhardware have different numbers of degrees of freedom that allowadjustment in rotation, or have different numbers of degrees of freedomthat allow adjustment in translation.
 11. The apparatus of claim 1further comprising mounting hardware which comprises first pin fixationhardware attachable to said arms and second pin fixation hardwareattachable to said arms, wherein said first pin fixation hardware andsaid second pin fixation hardware have different numbers of degrees offreedom that allow continuous adjustment, or have different numbers ofdegrees of freedom that allow discrete adjustment.
 12. The apparatus ofclaim 1, wherein said superior arm, said anterior arm and said posteriorarm have fixed angular relationships with each other such that if saidsuperior arm at least approximately aligns with a lower leg of apatient, said anterior arm at least approximately aligns with ananterior portion of a foot of the patient, and said posterior arm atleast approximately aligns with a posterior portion of said foot of thepatient.
 13. The apparatus of claim 1, wherein said superior arm andsaid anterior arm and said posterior arm are capable of occupying aplurality of angular positions with respect to each other around acentral axis hole that passes through a common intersection point withinsaid central region, said angular positions all being within a commonplane.
 14. The apparatus of claim 13, further comprising a lockingdevice, said locking device being capable of locking said superior arm,said anterior arm and said posterior arm in desired angular positionsrelative to each other.
 15. The apparatus of claim 14, wherein at leastsome of said angular positions are discretely defined angular positions,and wherein said locking device further comprises detents at saiddiscretely defined angular positions.
 16. The apparatus of claim 1,wherein at least one of said superior arm and said anterior arm and saidposterior arm contains a respective joint that is capable of allowing adistal portion of said at least one arm to rotate around the arm axis ofsaid at least one arm in such a way as to be able to occupy a pluralityof angular positions with respect to a central portion of saidrespective arm.
 17. The apparatus of claim 16, wherein the slot of saidat least one arm is located entirely within said distal portion of saidrespective arm.
 18. The apparatus of claim 16, wherein said superior armand said anterior arm and said posterior arm are capable of occupying aplurality of angular positions with respect to each other around acentral axis hole that passes through a common intersection point withinsaid central region, said angular positions all being within a commonplane.
 19. The apparatus of claim 16, further comprising a lockingdevice, said locking device being capable of locking a distal portion ofsaid arm with respect to a central portion of said at least one arm. 20.The apparatus of claim 1 wherein said superior arm axis, said anteriorarm axis and said posterior arm axis intersect at a common intersectionpoint within said central region and occupy a common plane.
 21. Theapparatus of claim 1 wherein said frame is integrally formed.
 22. Anapparatus for fixating at least one bone, said apparatus comprising: aframe comprising a superior arm, an anterior arm and a posterior arm,said superior arm, anterior arm and posterior arm extending outwardly inrespective different directions from a central region, said superior armhaving a superior arm axis extending generally along a lengthwisedirection of said superior arm through said central region, saidsuperior arm having therethrough a superior arm slot extending generallyalong at least a portion of a length of said superior arm and beinggenerally aligned with said superior arm axis, said anterior arm havingan anterior arm axis extending generally along a lengthwise direction ofsaid anterior arm through said central region, said anterior arm havingtherethrough an anterior arm slot extending generally along at least aportion of a length of said anterior arm and being generally alignedwith said anterior arm axis, said posterior arm having a posterior armaxis extending generally along a lengthwise direction of said posteriorarm through said central region, said posterior arm having therethrougha posterior arm slot extending generally along at least a portion of alength of said posterior arm and being generally aligned with saidposterior arm axis, wherein none of said superior arm axis, saidanterior arm axis and said posterior arm axis are collinear with eachother, and wherein each of said slots is configured to receive mountinghardware that is a) mountable on said arms through respective ones ofsaid slots, b) able to occupy a plurality of translational positionsalong said slots, and c) able to hold at least one bone-fixating pin,and wherein said mounting hardware comprises a clamp having a clampcross-hole having internal grooves having a clamp hole angular spacingtherebetween, and comprises a rocker nut having external teeth having arocker nut angular spacing therebetween, wherein one of said clamp holeangular spacing and said rocker nut angular spacing is an integermultiple of the other.